arm64: mvebu: Restrict memory size to a usable maximum

Not all memory is mapped in the MMU. So we need to restrict the memory
size so that U-Boot does not try to access it. Also, the internal
registers are located at 0xf000.0000 - 0xffff.ffff. Currently only 2GiB
are mapped for system memory. This is what we pass to the U-Boot
subsystem here.

Signed-off-by: Stefan Roese <[email protected]>
Cc: Nadav Haklai <[email protected]>
Cc: Neta Zur Hershkovits <[email protected]>
Cc: Kostya Porotchkin <[email protected]>
Cc: Omri Itach <[email protected]>
Cc: Igal Liberman <[email protected]>
Cc: Haim Boot <[email protected]>
Cc: Hanna Hawa <[email protected]>

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/arm/mach-mvebu/arm64-common.c b/arch/arm/mach-mvebu/arm64-common.c
index 1fc2ff2f7cf..8f026559c2f 100644
--- a/arch/arm/mach-mvebu/arm64-common.c
+++ b/arch/arm/mach-mvebu/arm64-common.c
@@ -17,6 +17,23 @@
 DECLARE_GLOBAL_DATA_PTR;
 
 /*
+ * Not all memory is mapped in the MMU. So we need to restrict the
+ * memory size so that U-Boot does not try to access it. Also, the
+ * internal registers are located at 0xf000.0000 - 0xffff.ffff.
+ * Currently only 2GiB are mapped for system memory. This is what
+ * we pass to the U-Boot subsystem here.
+ */
+#define USABLE_RAM_SIZE		0x80000000
+
+ulong board_get_usable_ram_top(ulong total_size)
+{
+	if (gd->ram_size > USABLE_RAM_SIZE)
+		return USABLE_RAM_SIZE;
+
+	return gd->ram_size;
+}
+
+/*
  * On ARMv8, MBus is not configured in U-Boot. To enable compilation
  * of the already implemented drivers, lets add a dummy version of
  * this function so that linking does not fail.